1. Field of the Invention
The present invention relates to a storage-based digital broadcast system that receives and stores data contents and AV (Audio-Visual) contents on the receiving side sent from the sending side and reproduces the data contents and AV contents, etc. in viewing, and a transmitter and a receiver used in the system, and in particular to a storage-based digital broadcast system wherein storage of contents on the receiving side and use restriction on the stored contents, etc. can be controlled per service provided by contents providers, and a transmitter and a receiver used in the system.
2. Description of the Related Art
In digital broadcasts, storage-based broadcast systems have been developed where programs and contents transmitted from the sending side are received and stored on the receiving side and users reproduce to view the programs and contents when it is convenient for them.
In this broadcast system, broadcast programs and the associated program additional information (contents) are transmitted and SI (Service Information) such as EIT (Event Information Table) and LIT (Local event Information Table) to define program scenes and ERT (Event Relation Table) to define relationship between scenes are broadcast as guidance information on programs, etc. On the receiving side, it is possible to receive and store broadcast programs and contents and use SI to reproduce for example only news programs from among stored programs and contents or to view a particular scene of a program.
In the future digital broadcasts, a broadcast form is expected where providers that create and provide contents will be separated from broadcast operators and that broadcast operators will only multiplex and transmit contents provided by contents providers.
Information indicating a contents provider and information on the services to which the contents belong will be described for individual contents.
The Japanese Patent Laid-Open No. H07-177109/(1995) indicates adding codes to a plurality of information pieces and determining the priority of display that is based on each code. A code used in this disclosure has an inherent meaning so that the meaning of the code cannot be changed later.
Terms used herein will be defined below.
AV (Audio-Visual) data: Stream format data such as image, voice and subtitle data.
Data contents: Non-stream format data associated with broadcast programs. For example, HTML, XML, BML, moving pictures (MPEG and MOV), still pictures (JPEG, GIF) are included. Individual contents can be identified using identifiers.
AV contents: AV data related to data contents among AV data. Individual AV contents can be identified using identifiers.
Contents: Data contents and AV contents, which partially reference each other.
Service: Information that groups contents.
In related art storage-based broadcast system s, it is not easily possible to automatically store in a receiver the contents that belong to a service provided by a contents provider, nor set or change the validity term of contents stored in the receiver for each service provided by the contents provider.
In case wishing to execute such processing in a related art system, it is necessary to describe information on the contents provider and the service to which the contents belong for individual program and all the contents. This results in transmission of huge data thus worsening the transmission efficiency.
In a related art system, it is impossible to describe the relationship between a plurality of contents providers to which the contents are related, or describe the relationship between a plurality of programs or contents that relate to each other.
In case a single provider is concerned, the contents are transmitted in various forms from various broadcast operators or in various service forms from a single broadcast operator, or separately with shifted timings due to limited transmission bandwidth. In this way, it is difficult to receive contents with the structure (relationship between contents) intended by the provider maintained.
Appending data that indicates the corresponding service to contents prevents change of service.
The invention solves such problems and aims at providing a broadcast system where storage of contents on the receiving side and use restriction on the stored contents, etc. can be implemented per service provided by contents providers and a transmitter and receiver used in the system.